Process of refining mineral oils



UNITED STATES" 1,540,218 PATENT OFFICE.

WILLIAM. T. MALONEY, OF CLEAN, NEW YORK.

PROCESS OF REFINING MINERAL QILS.

No Drawing.

To all whom it may concern:

Be it known that I, \VILLIAM T. MALONEY, a citizen of the United States,residing at Olean, in the county of Cattaraugus and State of New York,have invented certain new and useful Improvements in Processes ofRefining Mineral Oils, of which the following is a specification.

The present invention relates to the art of refining mineral oils, andmore particularly to a process which contemplates the intimateassociation of air, oxygen, or ozone with the oil whereby those elementsin the oil which readily combine with such oxidizing agents can beseparated from the oil by treatment with alkali, the hypochlorites ofthe alkalis, or sodium or potassium bisulfite, thereby forming aprecipitate, the reagent being recoverable with a minimum loss;-

In thecommon process of refining oils by the addition of sulphuric acidand agitation of the mixture, a quantity of sludge is formed which ispractically worthless, and from which a part of the original volume ofacid can only be recovered at considerable expense. I Further, aquantity of the oil combines with the acid in this process and iscarried off in the form of sludge, resulting in an appreciable decreasein the volume of refined oil as compared with the volume prior totreatment. The oil so made is, moreover. oxidizable and is thereforewholly unsuited for use in transformers until it has been subjected toother and expensive processes, or treated with such a large amount ofacid as to cause an enormous loss of oil.

It is the purpose of the present invention to manufacture by a cheap andeflicient process an oil which .is suitedto all conditions oflubrication, but which is more particularly adapted for use in electrictransformers. An oil for this purpose must possess qualities, not foundin the ordinary-lubricating oils. It must be incapable, or practicallyincapable of absorbing oxygen, and it must serve as an insulator as wellasa cooling medium in the transformer. Therefore it is necessary that itbe capable of withstanding electric currents of very: high voltage. Ifit cannot resist oxidation there will be a sludge formed which may cakearound the tlflHSfOlll'lCI coil, and, because of its thick and tarryconsistency there is a tend ency for the coil to become heated, and theoil likewise loses its insulating properties.

Application filed March s, 1924. Serial No. 700,167.

One of the objects of the present invention is to produce an oilsuitable for use in transformers which will not sludge when subjected tothe tests for such an oil. Any oil will sludge in a transformer in time,but ifo-an oil passes the usual tests it is called non-sludging.

Another object is to produce an'oil the volume of which is notappreciably diminished by treatment in the process of refinmg.

A further object is to so treat an oil with alkali the hypochlorites ofthe alkalis, or sodium or potassium bisulfitethat the re agent can berecovered for re-use with a minimum decrease in quantity and quality.

A still further object is to provide a process for refining mineral oilswhich is cheap and efficient, and" whichdoes not necessitate a change inthe present refinery equipment. In attaining these objects with thisprocess an. oil is produced which shows a marked improvement in color,demulsibility and oxidation tests, and, in the case of many oils, inviscosity and cold tests. The cost of producing such oil is cheapenedthrough a saving of oil, and also from the actual cost of treatment.

Oil is first introduced into an agitator of the conventional typecommonly used in the refining industry. It is then agitated, 'or blown,with air, oxygen, or ozone, the oil being either hot or cold. If airoroxygen is used for-blowing it is preferable that the oil be heated toa temperature not to exceed 50 Fahrenheit below its flash point, but

when ozone is used the oil may be cold, because the unusual activity ofozone will produce the same effect with equal efliciency and speed. Thisparticular treatment is not essential, but is desirable inasmuch as ithastens the absorption and combination of air, oxygen, or ozone, asthecase may be, with the oxidizable substances in the oil. The time ofagitation varies with the quality and amount of oil being treated, andthe temperature to which the oil is heated may be any temperature up to50 Fahrenheit below its flash point. This limit is set for the sake ofsafety, and also to prevent excessive decomposition.

Except in those cases where ozone is used,

it is preferable to use temperatures of 180" to 300 F. during theoxidation treatment, a

certain amount of heat being required to produce satisfactory results,

kalis, sodium or potassium bisulfite may also be advantageously used,or, in fact, any compound which, on hydration, gives an al kalinereaction. The selection of a reagent depends largely on its cost. Thesolvent used, in the case of any of the various reagents, is water.

When treated in this manner a flocculent precipitate is formed and suchprecipitation can be facilitated by heating the oil as it is agitated,although this step of the process can also be performed if the oil iscold. If

hot, however, the reagent settles out easily andmay then be drawn off.The treatment with alkali after oxidation is preferably carried out attemperatures of 180 to 200- F. It is advisable to continue this step ofthe process until thereis no further evidence of preci itation. Insettling out the alkaline solution sinks to the bottom of the agitatorwith very little diminution of its original volume. Above this solutionthere is a welldefined band of precipitate which increases in thicknessas the solution is cooled, either by artificial means or by beingallowed to stand. The alkaline solution may then be drawn off and isimmediately ready for re-.

use. To hasten precipitation it has been found advisable, in some cases,to add a little clay or similar material in theform of a fine powder andagitated-with the oil.

A After having been cooled sufficiently, the oil is separated from theprecipitate by means of a continuous filter, or by any other means offiltering, to remove the precipitate.

A variation of the process described above is accomplished with equalefiiciency in adding a small quantity of alkali, the hypochlorites ofthe alkalis, or sodium or potassium bisulfite before orduring theblowing with is' reliminary to both of the above. is as air, oxygen, orozone. It is best to introduee the reagent in the form of a solution inorder to insure a more intimate contact with the entire body of oil, thesolvent for the reagent bein water.

A stillurther variation, and one which fol ows The oil is well agitatedwith alkali, hypochlorites of the alkalis, or sodium or potassiumbisulfite, preferably in solution, and the excess reagent allowed tosettle to the bottom of the agitator where it is drawn off, or, ifdesired, allowed to remain in the oil. A 10% solution of sodiumcarbonate,

or soda ash, is very satisfactory and is cheaper than caustic soda. Atthis point it might be added that an eflicient solution for causingheavyprecipitation is a 35% to solution of caustic soda; These solutionsare not especially recommended, however, inasmuch as the variations inquality of the oil treated are considerable, and the particular strengthof solution must of necessity depend on the particular oil beingtreated, and

the conditions under which this treatment is taking place. 6

The mixture, or solution, of alkali, hypochlorites of the alkalis, orsodium or potassium bisulfite, and oil is next exposed to air, oxygen,or ozone either in shallow pans or in the ordinary storage tanks. Theuse of paris shortens the necessary time of exposure inasmuch as agreater surface of liquid is presented thereby hastening the action. Ifdone in storage tanks the time of exposure can be shortened by putting aslight pressure of air, oxygen, or ozone on the surface of the liquid.In the course of time, varying from one to several days depending on thequalities of the oil being treated, a precipitate will form, and the oilwill bebrighter and frequently of lighter color than the same oil whichhas been exposed to air, oxygen, or ozone, but which hasnot been treatedwith the reagent. In some cases the oil may then be filtered free of theprecipitate when it will be found to pass the desired tests as to colorand demulsibility. Often it is advantageous, after filtering, to againagitate the oil with a strong solution of alkaline reagent in the mannerfirst described. By strong solution I mean a 25 to solution.

The color of the oil'isdependent upon the amount of oxygen absorbed byit, and this, in turn, is dependent upon the time of exposure and thepressure of the oxygencontaining gas used. Test can be readily made todetermine when this stage has been reached.

If too high a temperature is reached in the preci itation with alkali,the hypoehlorites of t e alkalis, or sodium or potassium 'bisulfitethere is a tendency for. the oil to temporarily darken in color, butupon standing and cooling the good color is restored. Or, if desired,the oil may be washed with a hot, dilute solution of the reagent untilthere is no further improvement in its color, and then washed withwater. By dilute solution I mean a 5% solution, or even weaker.

It is then necessary to heat-the oil and blow the moisture out'with air,or by any other approved method. The judicious use of strong alkalinesolution shortens the time consumed in this step of the process byeliminating the necessity for such drying or brightening.

Ill)

The use of ozone in the process of purifibation is, particularlyadvantageous in the treatment of gasoline and transformer oil. Becauseof its volatility andextremely inflammable qualities gasoline'cannot besafely heated for treatment. The use of ozone en-' ables the process tobe carried on efiiciently without heat,'thereby eliminating the dangerfrom fire or explosion. In the making of transformer oil the best methodis to use ozone with warm, or even hot oil, with or without an additionof alkali. By using ozone the higher temperature required with air oroxygen is not necessary. Excessive an. I alkaline reagent.idizedsubstances.

heat is to be avoided "because of decomposition. In the case of someoils a preliminary light treatment with acid is advantageous before thisprocess is used.

No claim is made to particular apparatus for performing the processabove described for the reason that the ordinary refinery apparatus nowin use is suflicient for that purpose, except in the case of ozone theuse of which requires the installation of ozonizing, equipment.

' What is claimed is 1. The process of making transformer oil whichconsists of exposing mineral oil to the action of an oxygen containinggas to oxidize the sludging components, and adding to precipitate theox- 2. The processof making transformer oil which consists in exposingmineral oil to the action of an oxygen containing gas while heating, tooxidize the sludging components,"

and adding an alkaline reagent to precipitate the oxidized substances.

' 3. The process of making transformer oil which consists in exposingmineral oil to the action 'of an oxygen containing gas while heating, tooxidize the sludging components, and adding an alkaline reagent whileheating to precipitate the oxidized substances. 1

4. The process of making transformer oil which consists in exposingmineral oil to the action of an oxygen. cont ining gas to oxidize thesludging components,

and adding an alkaline reagent while heating, to precipitate theoxidized substances. 5. The process of making transformer oil whichconsists in exposing mineral oil to .agitation with analkaline solution,settling,

drawing off the excess of alkaline solution, exposing the treated oil tothe action of an oxygen containing gas to oxidize sludging I components,and filtering off any precipitate that is formed.

6. The process of producing transformer oil which consists in adding asmall quantity of alkaline reagent to the body of the oil and at thesame time agitating the oil with a gas containing oxygen, in nextagitating the oil with a concentrated alkaline solution, allowing thesolution to settle, and finally filtering the body of oil free from theprecipitatev reagent, and separating the precipitate formed by thereaction from the body of oil by filtration.

9. The process of producing transformer oils which consists in adding asmall quantity of alkali to mineral oil and simultaneously agitating theoil with ozone, then in agitating the oil with a strong alkalinesolution, in

allowing the solution so formed to settle,"

drawing oil the excess of alkaline solution, and finally filtering offany precipitate that has formed.

10. The process of producing transformer oils which consists in adding asmall quantity of alkali to mineral oil, while agitating the oil withozone, then Washing the oil with a dilute alkaline solution, in allowingthe solution to settle, and drawing off the excess of alkaline solution,and finally filtering off any precipitate that has formed.

In testimony whereof I- afiix my signature.

WILLIAM T. MALONEY;

